The major objective is to determine the pathways of metabolic activation and detoxification of the tobacco specific carcinogen, N'-nitrosonornicotine (NNN), to assess the effects of environmental modifiers on the induction of enzymes which mediate these transformations, and to conduct bioassyas (in conjunction with NNN) of modifiers having the greatest effect on activation pathways. The metabolites resulting from alpha-hydroxylation of NNN have now been identified. Since alpha-hydroxylation is a likely activation pathway for NNN, assays for NNN-alpha-hydroxylase activity will be developed and the induction of this enzyme by environmental modifiers will be studied. Bioassays of NNN in conjunction wih the most effective modifiers will commence. The beta-hydroxy and beta-oxo derivatives of NNN will be synthesized and assayed for mutagenicity and carcinogenicity and the metabolism of NNN by beta-hydroxylation will be studied.